ELASTIC ELECTRON HELIUM SCATTERING SPECTRA ASSISTED BY A CO 2 LASER FIELD

Abstract We have studied theoretically the electron spectra in the elastic scattering of a fast electrons (E i = 9.5 eV) by helium atoms in the presence of a CO 2 monochromatic laser field and in the presence of a CO 2 bichromatic laser field. The former is linearly polarized, and has moderate intensity (I=10 8 Wcm -2 ) with photon energy eV 117 . 0 = ω h . The latter has the same polarization and has two components of frequencies ω and 2ω which are out of phase by an arbitrary angle ϕ. Our numerical results (in the Born approximation) show that the scattered signal is sensitive to the collision geometry. Otherwise it is easily controllable by the phase variations, especially at the quadrature of the phase (ϕ = π/2) the signal in the presence of the CO 2 monochromatic laser can be reproduced by a CO 2 bichromatic laser field with less intensity what would be a great advantage in laser spectroscopy